A Florida mother launched her own "To Catch a Predator"-style sting operation when her 11-year-old daughter began receiving pornographic text messages from an adult man and police told her they needed more evidence to make an arrest.

The St. Petersburg, Fla., girl set up a Facebook account and friended Michael Bradley, whom she later gave her phone number, police and the girl's mother said.

Bradley, 23, allegedly texted the girl for several weeks with increasingly inappropriate and graphic messages. He asked whether she was still a virgin, wanted sex for her birthday and she'd skip school to meet him, police said.

"It got out of control very quick, just out of control," the mother, who asked not be identified to protect her daughter, told ABC News affiliate WFTS-TV.

The mother says she called the man and asked him to stop contacting her daughter. He denied the allegation and told the woman his 15-year-old brother had written the texts, police said.

The mom went to police with copies of the texts and the Bradleys' phone number, she said, but cops told her it wasn't sufficient to arrest him.

"Just because someone texts something inappropriate doesn't mean there's sufficient evidence for an arrest," St. Petersburg police spokesman Michael Puetz told ABC News.com. "First, we have to establish the suspect is the person sending that text. Just because it's a particular phone number doesn't suffice. You need more evidence."

When police said there was little more they could do, the mother says she took matters into her own hands.

"So, I thought, I got to go the extra mile, I have got to take the extra steps to make sure my child is safe," she said.

Pretending to be her daughter, the mother continued engaging Bradley in conversation. When he allegedly asked for a photo, she sent him an image of a teenage model from a Target advertisement.

"That's when he sent the shots of a whole naked body," the mother alleged.

But that still wasn't enough to prove who was responsible for sending the images, police told her. So the mom asked for a picture of Bradley's face.

"When she received the photos with the suspect's face, that changed the dynamic," Puetz said. "Now we could identify the individual and make an arrest."

The mother, however, said she was frustrated by the inability of police to act quickly.

"I think it should have been acted on more quickly," she said.

Arrested Monday, Bradley was charged on 16 counts, including unlawful use of a two-way communications device and distributing obscene material to a minor.

He is being held and does not yet have a lawyer, police said. He has not entered a plea and will appear in count Friday.